汽车大梁后减震器盒开裂原因

Cracking Cause of Rear Shock Absorber Box

针对510L热轧板生产卡车大梁后减震器盒在冲压成型后其转角处盒壁上端位置出现开裂的情况,对开裂零件进行了金相、扫描电镜、化学、力学等检验分析工作。分析发现落料后冲压板材未修边,成型过程中转角位置金属流动性差,堆积的金属在内侧壁上凸起,在拉应力作用下导致未修边的剪切边上的细小剪切裂纹撕裂。由于成型过程中润滑不良、位置偏差等原因使得凸模与盒壁产生了较大的附加应力,使得前述撕裂的裂纹在该应力作用下扩展形成宏观开裂。

Cracking was found at the upper end of the wall in the corner positions of a rear shock absorber box of the automobile frame after stamping of the blank of 510L hot-rolled plate. Cracked sample was analyzed by optical mi- croscopy, scanning electron micsoscopy （SEM）, mechanical and chemical analysis. It was found that the rear shock absorber box stamped directly with sheared blank was torn by the tensile stress induced by the bulging of metal in the inner wall of the box due to the poor metal flow at the corner positions. The aforementioned torn crack was fur- ther propagated to macroscopic crack resulted from the additional tensile stress caused by the friction between the terrace die and the wall of the box owing to poor lubrication and positional deviation during stamping.